/* ref.c: REFERENCES
*
* $Id: //info.ravenbrook.com/project/mps/custom/cet/main/code/ref.c#3 $
* Copyright (c) 2001-2016 Ravenbrook Limited. See end of file for license.
*
* .purpose: Implement operations on Ref, RefSet, ZoneSet, and Rank.
*
* .design: See design.mps.ref and design.mps.refset.
*/
#include "mpm.h"
SRCID(ref, "$Id: //info.ravenbrook.com/project/mps/custom/cet/main/code/ref.c#3 $");
/* RankCheck -- check a rank value */
Bool RankCheck(Rank rank)
{
CHECKL(rank < RankLIMIT);
UNUSED(rank); /* <code/mpm.c#check.unused> */
return TRUE;
}
/* RankSetCheck -- check a rank set */
Bool RankSetCheck(RankSet rankSet)
{
CHECKL(rankSet < ((ULongest)1 << RankLIMIT));
UNUSED(rankSet); /* <code/mpm.c#check.unused> */
return TRUE;
}
/* ZoneSetOfRange -- calculate the zone set of a range of addresses */
ZoneSet ZoneSetOfRange(Arena arena, Addr base, Addr limit)
{
Word zbase, zlimit;
AVERT(Arena, arena);
AVER(limit > base);
/* The base and limit zones of the range are calculated. The limit */
/* zone is the zone after the last zone of the range, not the zone of */
/* the limit address. */
zbase = (Word)base >> arena->zoneShift;
zlimit = (((Word)limit-1) >> arena->zoneShift) + 1;
/* If the range is large enough to span all zones, its zone set is */
/* universal. */
if (zlimit - zbase >= MPS_WORD_WIDTH)
return ZoneSetUNIV;
zbase &= MPS_WORD_WIDTH - 1;
zlimit &= MPS_WORD_WIDTH - 1;
/* If the base zone is less than the limit zone, the zone set looks */
/* like 000111100, otherwise it looks like 111000011. */
if (zbase < zlimit)
return ((ZoneSet)1<<zlimit) - ((ZoneSet)1<<zbase);
else
return ~(((ZoneSet)1<<zbase) - ((ZoneSet)1<<zlimit));
}
/* ZoneSetOfSeg -- calculate the zone set of segment addresses
*
* .rsor.def: The zone set of a segment is the union of the zones the
* segment occupies.
*/
ZoneSet ZoneSetOfSeg(Arena arena, Seg seg)
{
/* arena is checked by ZoneSetOfRange */
AVERT(Seg, seg);
return ZoneSetOfRange(arena, SegBase(seg), SegLimit(seg));
}
/* RangeInZoneSetFirst -- find an area of address space within a zone set
*
* Given a range of addresses, find the first sub-range of at least size that
* is also within a zone set. i.e. ZoneSetOfRange is a subset of the zone set.
* Returns FALSE if no range satisfying the conditions could be found.
*/
static Addr nextStripe(Addr base, Addr limit, Arena arena)
{
Addr next = AddrAlignUp(AddrAdd(base, 1), ArenaStripeSize(arena));
AVER(next > base || next == (Addr)0);
if (next >= limit || next < base)
next = limit;
return next;
}
Bool RangeInZoneSetFirst(Addr *baseReturn, Addr *limitReturn,
Addr base, Addr limit,
Arena arena, ZoneSet zoneSet, Size size)
{
Size zebra;
Addr searchLimit;
AVER(baseReturn != NULL);
AVER(limitReturn != NULL);
AVER(base < limit);
AVERT(Arena, arena);
AVER(size > 0);
AVER(zoneSet != ZoneSetEMPTY);
/* TODO: Consider whether this search is better done by bit twiddling
zone sets, e.g. by constructing a mask of zone bits as wide as the
size and rotating the zoneSet. */
if (AddrOffset(base, limit) < size)
return FALSE;
if (zoneSet == ZoneSetUNIV) {
*baseReturn = base;
*limitReturn = limit;
return TRUE;
}
/* A "zebra" is the size of a complete set of stripes. */
zebra = (sizeof(ZoneSet) * CHAR_BIT) << ArenaZoneShift(arena);
if (size >= zebra) {
AVER(zoneSet != ZoneSetUNIV);
return FALSE;
}
/* There's no point searching through the zoneSet more than once. */
searchLimit = AddrAdd(AddrAlignUp(base, ArenaStripeSize(arena)), zebra);
if (searchLimit > base && limit > searchLimit)
limit = searchLimit;
do {
Addr next;
/* Search for a stripe in the zoneSet and within the block. */
/* (Find the first set bit in the zoneSet not below the base zone.) */
while (!ZoneSetHasAddr(arena, zoneSet, base)) {
base = nextStripe(base, limit, arena);
if (base >= limit)
return FALSE;
}
/* Search for a run stripes in the zoneSet and within the block. */
/* (Find a run of set bits in the zoneSet.) */
next = base;
do
next = nextStripe(next, limit, arena);
while (next < limit && ZoneSetHasAddr(arena, zoneSet, next));
/* Is the run big enough to satisfy the size? */
if (AddrOffset(base, next) >= size) {
*baseReturn = base;
*limitReturn = next;
return TRUE;
}
base = next;
} while (base < limit);
return FALSE;
}
/* RangeInZoneSetLast -- find an area of address space within a zone set
*
* Given a range of addresses, find the last sub-range of at least size that
* is also within a zone set. i.e. ZoneSetOfRange is a subset of the zone set.
* Returns FALSE if no range satisfying the conditions could be found.
*/
static Addr prevStripe(Addr base, Addr limit, Arena arena)
{
Addr prev;
AVER(limit != (Addr)0);
prev = AddrAlignDown(AddrSub(limit, 1), ArenaStripeSize(arena));
AVER(prev < limit);
if (prev < base)
prev = base;
return prev;
}
Bool RangeInZoneSetLast(Addr *baseReturn, Addr *limitReturn,
Addr base, Addr limit,
Arena arena, ZoneSet zoneSet, Size size)
{
Size zebra;
Addr searchBase;
AVER(baseReturn != NULL);
AVER(limitReturn != NULL);
AVER(base < limit);
AVERT(Arena, arena);
AVER(size > 0);
AVER(zoneSet != ZoneSetEMPTY);
/* TODO: Consider whether this search is better done by bit twiddling
zone sets, e.g. by constructing a mask of zone bits as wide as the
size and rotating the zoneSet. */
if (AddrOffset(base, limit) < size)
return FALSE;
if (zoneSet == ZoneSetUNIV) {
*baseReturn = base;
*limitReturn = limit;
return TRUE;
}
/* A "zebra" is the size of a complete set of stripes. */
zebra = (sizeof(ZoneSet) * CHAR_BIT) << ArenaZoneShift(arena);
if (size >= zebra) {
AVER(zoneSet != ZoneSetUNIV);
return FALSE;
}
/* There's no point searching through the zoneSet more than once. */
searchBase = AddrSub(AddrAlignDown(limit, ArenaStripeSize(arena)), zebra);
if (searchBase < limit && base < searchBase)
base = searchBase;
do {
Addr prev;
/* Search for a stripe in the zoneSet and within the block. */
/* (Find the last set bit in the zoneSet below the limit zone.) */
while (!ZoneSetHasAddr(arena, zoneSet, AddrSub(limit, 1))) {
limit = prevStripe(base, limit, arena);
if (base >= limit)
return FALSE;
}
/* Search for a run stripes in the zoneSet and within the block. */
/* (Find a run of set bits in the zoneSet.) */
prev = limit;
do
prev = prevStripe(base, prev, arena);
while (prev > base && ZoneSetHasAddr(arena, zoneSet, AddrSub(prev, 1)));
/* Is the run big enough to satisfy the size? */
if (AddrOffset(prev, limit) >= size) {
*baseReturn = prev;
*limitReturn = limit;
return TRUE;
}
limit = prev;
} while (base < limit);
return FALSE;
}
/* ZoneSetBlacklist() -- calculate a zone set of likely false positives
*
* We blacklist the zones that could be referenced by values likely to be
* found in ambiguous roots (such as the stack) and misinterpreted as
* references, in order to avoid nailing down objects. This isn't a
* perfect simulation, but it should catch the common cases.
*/
ZoneSet ZoneSetBlacklist(Arena arena)
{
ZoneSet blacklist;
union {
mps_word_t word;
mps_addr_t addr;
int i;
long l;
} nono;
AVERT(Arena, arena);
blacklist = ZoneSetEMPTY;
nono.word = 0;
nono.i = 1;
blacklist = ZoneSetAddAddr(arena, blacklist, nono.addr);
nono.i = -1;
blacklist = ZoneSetAddAddr(arena, blacklist, nono.addr);
nono.l = 1;
blacklist = ZoneSetAddAddr(arena, blacklist, nono.addr);
nono.l = -1;
blacklist = ZoneSetAddAddr(arena, blacklist, nono.addr);
return blacklist;
}
/* C. COPYRIGHT AND LICENSE
*
* Copyright (C) 2001-2016 Ravenbrook Limited <http://www.ravenbrook.com/>.
* All rights reserved. This is an open source license. Contact
* Ravenbrook for commercial licensing options.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* 3. Redistributions in any form must be accompanied by information on how
* to obtain complete source code for this software and any accompanying
* software that uses this software. The source code must either be
* included in the distribution or be available for no more than the cost
* of distribution plus a nominal fee, and must be freely redistributable
* under reasonable conditions. For an executable file, complete source
* code means the source code for all modules it contains. It does not
* include source code for modules or files that typically accompany the
* major components of the operating system on which the executable file
* runs.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
* PURPOSE, OR NON-INFRINGEMENT, ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDERS AND CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/